The present invention relates to a pump assembly and, more specifically, to a pump assembly having a new and an improved multilayer pressure plate.
A known slipper-type pump is disclosed in U.S. Pat. No. 3,200,752. This known slipper type pump has a pressure plate which is disposed in abutting engagement with the outer ring and adjacent to the rotor of a pumping element cartridge. A pair of inlet ports in the pressure plate are connected in fluid communication with each other along a path which includes a passage formed in a valve plate. Similarly, a pair of outlet ports in the pressure plate are connected in fluid communication with each other along a path which includes another passage formed in the valve plate. The forming of the various plate passages contributes substantially to the cost of making this known pump.
Another known pump is disclosed in U.S. Pat. No. 3,671,143. This pump includes a pressure plate which is made up of two plate members formed of powdered metal. The plate members are sintered or fused together to form a firm bond between the two plates. Passages are provided in the two plates to conduct fluid between a pair of outlet ports.